The present invention relates to the compaction of paved surfaces which have an inclined and/or curved profile in vertical cross section. A typical surface in this category is an asphalt automotive test track.
As is well known, a slope face is paved by laying a paving material on a graded slope with a machine known in the art as an asphalt finisher or "paver." Then, the laid asphalt is compacted by a vehicle known as a "roller" which has steel wheels or rubber tires. As shown in FIG. 4, a roller vehicle B runs on a slope face D, performing the compacting work while it is connected to and supported by a wire W which extends from an anchor vehicle A which runs along the top of the slope.
In a test course for automobiles, the roadbed is generally paved by machines which move in the travel direction of the test course. The compacting rollers and the like are run in the same travel direction to perform the roller-pressurizing work.
Since the test course has a special three-dimensional curved surface, the radii of curvature of the curved surfaces of the slope bottom portion and of the slope shoulder portion largely differ across the width of each profile of the course, i.e. in each vertical plane which is transverse to the longitudinal travel direction. These radii also sequentially vary from one profile to another taken along the course. Therefore, it is fairly difficult to roller-pressurize a curved surface to conform accurately to the designed profile. In particular, if the pressure-applying surfaces of steel roller wheels do not completely coincide with the surface of the asphalt mixture, the shape of the curved surface may change after it is rolled and an accurate paved surface cannot be obtained. Conventional compacting systems do not have wheels capable of conforming to the surfaces with curved profiles.
In an apparatus for rolling curved surfaces disclosed in the Official Gazette of Japanese Patent Publication No. 3024/1969 (JP-B 44-3024), the wheels are forcedly inclined by an hydraulic cylinder. Therefore, no problem will occur if the designed radius of curvature of the roadway profile is constant. If the radius of curvature sequentially varies from one position to another along the length of the roadway as in an easement curve portion of a test course, it is necessary to continuously change the angles of inclination of the wheels in accordance with the movement of the roller vehicle in its longitudinal direction of travel. However, it is extremely difficult to control the pressure of the hydraulic cylinder in such a manner.
When a roller is supported from an anchor vehicle by a wire on an ordinary hydraulic winch, the distribution of weight on the right and left wheels will differ due to the inclination of the roller main body, thus preventing uniform roller pressurization. Therefore, it is necessary to offset the deflected load of the roller by the tension of the wire rope of the winch. However, since the tension of a conventional winch is adjusted by manually operated controls, equal distribution of weight on the left and right wheels cannot be accurately maintained.